The present invention relates to a novel disk tilling implement of the type comprising a plurality of gangs of disks, the disks in each gang rotating about a common axis.
Tilling implements are already known that comprise gangs of common axis disks, which gangs are put into rotation independently of one another or together when they are moved in the tilling direction while bearing against the ground at the same time as they move or turn over the earth.
In particular, Redares"" French patent No. 2 666 484 discloses a stubble-burying implement having two inclined parallel rows of disks in the form of spherical caps situated at the front and a third row of disks of the same shape situated at the rear of the implement and inclined in a direction opposite to that of the first two rows.
Such an implement serves to chop up and mix stubble with earth over a shallow depth using the two rows of concave disks situated at the front, while the row of larger diameter concave disks situated at the rear serves to bury the stubble in the ground.
By virtue of its structure and its purpose (breaking up and burying stubble) such an implement cannot be considered as a genuine tilling implement which needs to work the ground to a greater depth in a manner that is uniform while ensuring that a plane and continuous surface is not formed to mark the boundary between a surface portion of the ground which has been tilled and the deeper portion of the ground which has not.
In general, such implements present the drawback of creating buildups or shortages of earth at the ends of the rows of disks because during tilling the earth is moved laterally relative to the axis of the implement.
Tilling implements are also known which comprise two gangs of disks placed side by side but presenting the drawback of working the earth poorly in the zone situated at the ends of the two gangs of disks which are close together.
Various types of disk are also known for mounting on tilling implements which are substantially in the form of spherical caps with peripheries that can present a series of shallow notches, of concave lobes, or of deep notches giving the disks the appearance of a multi-bladed propeller.
The present invention provides a novel tilling implement which uses simple and effective means to avoid the above drawbacks.
In its simplest embodiment, the present invention provides a tilling implement of the type comprising at the front at least two gangs of disks whose axes are parallel to each other and inclined relative to a direction perpendicular to the direction of advance of the tilling implement, and at the rear at least one gang of disks whose axis is inclined in a direction opposite to that of the front gangs, said tilling implement being characterized by the facts: that the disks of the front gangs are multi-lobed disks; that the disks of the rear gang(s) are multi-lobed disks or disks in the form of multiple blades or flails; that the disks in any one gang are equidistant; and that the disks of any given gang are situated, when seen in the direction of advance of the implement, between the disks of the preceding gang so as to pass between their tracks.
In a preferred embodiment of the invention, the disks of a gang are of a diameter that increases with increasing number of gangs of disks ahead of said gang on the implement.
In accordance with the invention, it can be advantageous to enable the gangs of disks which are at the front to rest freely on the ground, being free to move in the vertical direction relative to the frame of the tilling implement, whereas the gangs of disks situated at the rear are held in a position that is fixed relative to the tilling implement, thereby constraining them to work at a determined height relative to the ground.
In the invention, when the disks of the group of gangs which are situated at the front are in the form of spherical caps with edges cut out in the form of slightly rounded lobes, it is advantageous for the disks of the gang situated behind said group to be constituted by spherical caps which present deep notches so as to form multiple blades or flails in the disks.
It can be advantageous to place a disk of larger diameter at the rear end of a gang of disks situated at the front and at the front end of the gang of disks situated at the rear, thus making it possible to have a tilled surface that is more plane.
Similarly, in accordance with the invention, it can be advantageous to place a few disks of decreasing diameter at the front end of a gang of disks situated at the front and at the rear end of a gang of disks situated at the rear so as to decrease the amount of tilling work performed at said ends.
Because, in accordance with the invention, the disks of a gang of disks are situated between two disks of the preceding gang of disks when seen in the forward direction (each disk performs its work between the traces of the two disks that precede it), the invention makes it possible to perform work uniformly over the entire tilled surface and avoids forming furrows of the kind that are usually formed with presently known tilling implements of this type.
This result is further improved if the disks in the same gang are fixed helically on their common axis, each disk being offset e.g. through one-fourth or one-eighth of a turn relative to its neighbor.
In the invention, it is also preferable for the disks of the various gangs to have different numbers of lobes or of flails and/or for their helical mounting on the axes of different pairs of gangs to be performed at different pitches.
This is highly effective in avoiding the formation of a xe2x80x9chorizonxe2x80x9d, i.e. a plane interface between earth which has been tilled and earth which has not, and this is essential for keeping the earth in a well-cultivated state.
In accordance with the invention, it can be advantageous at the ends of the gangs of disks to provide a limited number of disks which are spaced further apart from one another than the other disks of the gang. Under such circumstances, it is preferable to space apart in this way disks that correspond in the various gangs so that any one disk continues to work between the tracks of the two disks of the preceding gang of disks.
In accordance with the invention, it is also possible to place an isolated disk of larger diameter on the axis of the tilling implement behind the first group of gangs of disks, thereby providing additional work on the ground while contributing to overall stability by compensating torque tending to cause the tilling implement to pivot about a vertical axis.
In a variant, it is possible for this purpose to use a flat disk acting as a rotary colter which stabilizes and holds the tilling implement on its travel direction, or indeed a plough share.
In another embodiment of the invention, instead of providing the tilling implement with a single plurality of gangs of disks which are mounted behind one another as described above, the tilling implement has two pluralities of such gangs of disks which are disposed substantially symmetrically about the travel axis of the tilling implement in such a manner that the gangs of disks are disposed in pairs, with the pairs situated at the front of the implement when seen from above presenting a V-shape that is open towards the front of the implement while the pairs of disks situated at the rear of the implement, seen from above, present a V-shape whose tip is directed towards the front of the implement.
In this embodiment, it is advantageous for the pairs of V-shaped disk gangs that are encountered in succession on going from the front towards the rear of the tilling implement to be offset alternately to the left and to the right so that the ground is worked in satisfactory manner in the vicinity of the axis of the tilling implement.
In a variant of this embodiment, the gangs of disks in a given pair of disks are offset relative to each other in the direction of advance of the tilling implement.
This disposition makes it possible to prevent the earth situated on the tilling axis being continuously between the central ends of the two gangs of disks in the same pair.